Display device

ABSTRACT

A display device includes a display panel, a metal plate disposed on a bottom surface of the display panel and configured to support the display panel, a filling member disposed on the bottom surface of the display panel, the filling member being disposed on the same level as the metal plate relative to the bottom surface of the display panel, and a material of the metal plate being different from a material of the filling member, a fingerprint sensor disposed on a bottom surface of the filling member, and a member-sensor bonding member disposed between the fingerprint sensor and the filling member to bond the fingerprint sensor to the filling member. A hardness of the filling member is greater than a hardness of the member-sensor bonding member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2020-0102891 filed on Aug. 17, 2020 in the Korean IntellectualProperty Office, and all the benefits accruing therefrom under 35 U.S.C.119, the contents of which in its entirety are herein incorporated byreference.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device, more particularly,to a display device with a filling member.

2. Description of the Related Art

A display device is applied to various electronic devices such as asmartphone, a tablet, a notebook computer, a monitor, and a television(TV). With the recent advance of mobile communication technology, theuse of portable electronic devices such as a smartphone, a tablet, and anotebook computer has increased enormously. Privacy information isstored in the portable electronic device. Accordingly, to protect theprivacy information of the portable electronic device, fingerprintauthentication in which a fingerprint as user's biometric information isused for authentication has been used. To this end, the display devicemay include a fingerprint sensor for fingerprint authentication.

The fingerprint sensor may be implemented as an optical sensor, anultrasonic sensor, a capacitive sensor, or the like. The fingerprintsensor is disposed under a display panel of the display device, andseveral members may be disposed between the display panel and thefingerprint sensor. An incident signal emitted from the fingerprintsensor is reflected from the user's fingerprint and received back in theform of a reflected signal by the fingerprint sensor. The amount ofattenuation of the incident signal and the reflected signal may varydepending on the physical properties of the several members which arepresent between the fingerprint sensor and the display panel.

SUMMARY

Aspects of the present disclosure provide a display device including afingerprint sensor with improved reliability.

According to an embodiment of the present inventive concept, a displaydevice includes a display panel, a metal plate disposed on a bottomsurface of the display panel and configured to support the displaypanel, a filling member disposed on the bottom surface of the displaypanel, the filling member being disposed on the same level as the metalplate relative to the bottom surface of the display panel, and amaterial of the metal plate being different from a material of thefilling member, a fingerprint sensor disposed on a bottom surface of thefilling member, and a member-sensor bonding member disposed between thefingerprint sensor and the filling member to bond the fingerprint sensorto the filling member. A hardness of the filling member is greater thana hardness of the member-sensor bonding member.

According to an embodiment of the present inventive concept, a displaydevice includes a display panel in which a main region, a sub-regionhaving an area smaller than that of the main region, and a bendingregion are defined, the bending region being disposed between the mainregion and the sub-region, and a portion of the display panel in themain region and a portion of display panel in the sub-region overlappingeach other in a thickness direction of the display device, a fillingmember disposed on a first surface of the display panel in the mainregion, a lower panel sheet disposed on a first surface of the fillingmember in the main region and on a first surface of the display panel inthe main region, the lower panel sheet being provided with a sheet holepenetrating the lower panel sheet in the thickness direction of thedisplay device, a fingerprint sensor disposed on the first surface ofthe filling member in the main region, and a member-sensor bondingmember disposed between the fingerprint sensor and the first surface ofthe filling member to bond the fingerprint sensor to the filling member.The sheet hole of the lower panel sheet exposes an inner side surface ofthe lower panel sheet. The fingerprint sensor overlaps, in the thicknessdirection of the display device, a first region defined by the sheethole. A hardness of the filling member is greater than a hardness of themember-sensor bonding member.

However, aspects of the present disclosure are not limited to the oneset forth herein. The above and other aspects of the present disclosurewill become more apparent to one of ordinary skill in the art to whichthe present disclosure pertains by referencing the detailed descriptionof the present disclosure given below.

In accordance with the display device including the fingerprint sensoraccording to embodiments, it is possible to improve the reliability ofthe fingerprint sensor.

The effects of the present disclosure are not limited to theaforementioned effects, and various other effects are included in thepresent specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present disclosure willbecome more apparent by describing in detail embodiments thereof withreference to the attached drawings, in which:

FIG. 1 is a perspective view illustrating a display device according toan embodiment of the present inventive concept;

FIG. 2 is an exploded perspective view showing a display deviceaccording to an embodiment of the present inventive concept;

FIG. 3 is a plan view illustrating a display panel, a display circuitboard, and a display driving circuit of FIG. 2 according to anembodiment of the present inventive concept;

FIG. 4 is an exemplary cross-sectional view of the display panel of FIG.3 according to an embodiment of the present inventive concept;

FIG. 5 is a cross-sectional view taken along line I-I′ of FIG. 3according to an embodiment of the present inventive concept;

FIG. 6 is a plan view illustrating a lower metal sheet and a fillingmember according to an embodiment of the present inventive concept;

FIG. 7 is an enlarged cross-sectional view of area A of FIG. 5 accordingto an embodiment of the present inventive concept;

FIG. 8 is an enlarged cross-sectional view of area B of FIG. 5 accordingto an embodiment of the present inventive concept;

FIG. 9 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 10 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 11 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 12 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 13 is a cross-sectional view illustrating a partial area of across-sectional view of a display device according to an embodiment ofthe present inventive concept;

FIG. 14 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 15 is a cross-sectional view showing a modified example of thefilling member of FIG. 8 according to an embodiment of the presentinventive concept;

FIG. 16 is a cross-sectional view of a display device according toaccording to an embodiment of the present inventive concept;

FIG. 17 is a cross-sectional view of a display device according to anembodiment of the present inventive concept;

FIG. 18 is a plan view illustrating a lower panel sheet and a displaypanel of FIG. 17 according to an embodiment of the present inventiveconcept;

FIG. 19 is a cross-sectional view of a display device according to anembodiment of the present inventive concept;

FIG. 20 is a plan view of a display device according to an embodiment ofthe present inventive concept;

FIG. 21 is a cross-sectional view of a part of a main region, a bendingregion, and a part of a sub-region of FIG. 20 according to an embodimentof the present inventive concept;

FIG. 22 is a cross-sectional view of a display device according to anembodiment of the present inventive concept;

FIG. 23 is a cross-sectional view of a display device according to anembodiment of the present inventive concept; and

FIG. 24 is a cross-sectional view of a display device according to anembodiment of the present inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Specific structural and functional descriptions of embodiments of theinvention disclosed herein are only for illustrative purposes of theembodiments of the invention. The invention may be embodied in manydifferent forms without departing from the spirit and significantcharacteristics of the invention. Therefore, the embodiments of theinvention are disclosed only for illustrative purposes and should not beconstrued as limiting the invention. That is, the invention is onlydefined by the scope of the claims.

It will be understood that when an element is referred to as beingrelated to another element such as being “coupled” or “connected” toanother element, it can be directly coupled or connected to the otherelement or intervening elements may be present therebetween. Incontrast, it should be understood that when an element is referred to asbeing related to another element such as being “directly coupled” or“directly connected” to another element, there are no interveningelements present. Other expressions that explain the relationshipbetween elements, such as “between,” “directly between,” “adjacent to,”or “directly adjacent to,” should be construed in the same way.

Throughout the specification, the same reference numerals will refer tothe same or like parts.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein,“a”, “an,” “the,” and “at least one” do not denote a limitation ofquantity, and are intended to include both the singular and plural,unless the context clearly indicates otherwise. For example, “anelement” has the same meaning as “at least one element,” unless thecontext clearly indicates otherwise. “At least one” is not to beconstrued as limiting “a” or “an.” “Or” means “and/or.” As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items. It will be further understood that theterms “comprises” and/or “comprising,” or “includes” and/or “including”when used in this specification, specify the presence of statedfeatures, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10% or 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Hereinafter, embodiments of the invention will be described withreference to the attached drawings.

FIG. 1 is a perspective view illustrating a display device according toan embodiment. FIG. 2 is an exploded perspective view showing a displaydevice according to an embodiment.

Referring to FIGS. 1 and 2, a display device 10 according to anembodiment may be applied to portable electronic devices such as amobile phone, a smartphone, a tablet personal computer, a mobilecommunication terminal, an electronic organizer, an electronic book, aportable multimedia player (PMP), a navigation system, an ultra mobilePC (UMPC) or the like. Alternatively, the display device 10 according toan embodiment may be applied as a display unit of a television, alaptop, a monitor, a billboard, or an Internet-of-Things (IoT) terminal.Alternatively, the display device 10 according to an embodiment may beapplied to wearable devices such as a smart watch, a watch phone, aglasses type display, or a head mounted display (HMD). Alternatively,the display device 10 according to an embodiment may be applied to adashboard of a vehicle, a center fascia of a vehicle, a centerinformation display (CID) disposed on a dashboard of a vehicle, a roommirror display in place of side mirrors of a vehicle, or a displaydisposed on a rear surface of a front seat for rear seat entertainmentof a vehicle.

In the present disclosure, a first direction DR1 may be a short sidedirection of the display device 10, for example, a horizontal directionof the display device 10. A second direction DR2 may be a long sidedirection of the display device 10, for example, a vertical direction ofthe display device 10. A third direction DR3 may be a thicknessdirection of the display device 10. The third direction DR3 may also bereferred to as the term “vertically”.

The display device 10 may have a planar shape similar to a rectangularshape. For example, the display device 10 may have a planar shapesimilar to a rectangular shape having short sides in the first directionDR1 and long sides in the second direction DR2, as shown in FIG. 1. Acorner where the short side in the first direction DR1 and the long sidein the second direction DR2 meet may be right-angled or rounded with apredetermined curvature. The planar shape of the display device 10 isnot limited to a rectangular shape, and may be formed in a shape similarto another polygonal shape, a circular shape, or elliptical shape.

The display device 10 may be formed flat. Alternatively, the displaydevice 10 may be formed such that two sides facing each other arebendable. For example, the display device 10 may be formed such that theleft and right sides are bendable. Alternatively, the display device 10may be formed such that all of the upper, lower, left, and right sidesare bendable.

The display device 10 according to an embodiment includes a cover window100, a display panel 300, a display circuit board 310, a display drivingcircuit 320, a fingerprint sensor 400, a bracket 600, a main circuitboard 700, and a lower cover 900.

The cover window 100 may be disposed above the display panel 300 tocover the front surface of the display panel 300. Accordingly, the coverwindow 100 may function to protect the top surface of the display panel300. For user authentication, a user's finger may touch a region of thecover window 100.

The cover window 100 may include a light transmitting portion DA100corresponding to the display panel 300 and a light blocking portionNDA100 corresponding to an area other than the display panel 300. Thelight blocking portion NDA100 may be formed to be opaque. Alternatively,the light blocking portion NDA100 may be formed as a decorative layerhaving a pattern that can be displayed to the user when an image is notdisplayed.

The display panel 300 may be disposed below the cover window 100. Thedisplay panel 300 may be a light emitting display panel including alight emitting element. For example, the display panel 300 may be anorganic light emitting display panel using an organic light emittingdiode including an organic light emitting layer, a micro light emittingdiode display panel using a micro LED, a quantum dot light emittingdisplay panel using a quantum dot light emitting diode including aquantum dot light emitting layer, or an inorganic light emitting displaypanel using an inorganic light emitting element including an inorganicsemiconductor. The following description is directed to the case wherethe display panel 300 is an organic light emitting display panel.

The display panel 300 may include a main region MA and a sub-region SBA.

The main region MA may include a display area DA displaying an image anda non-display area NDA that is a peripheral area of the display area DA.The display area DA may include display pixels (‘SP’ in FIG. 3) fordisplaying an image. The non-display area NDA may be defined as an areafrom the boundary of the display area DA to the edge of the displaypanel 300.

The display area DA may include a fingerprint sensing area. Thefingerprint sensing area indicates an area where the fingerprint sensor400 is disposed. The fingerprint sensing area may be a partial area ofthe display area DA as shown in FIG. 2. The fingerprint sensor 400 mayinclude, for example, an optical fingerprint sensor, an ultrasonicfingerprint sensor, or a capacitive fingerprint sensor. The followingdescription is directed to the case where an ultrasonic fingerprintsensor is applied as the fingerprint sensor 400.

The planar shape of the main region MA of the display panel 300 may be arectangular shape. For example, the planar shape of the main region MAmay have a rectangular shape with right-angled corners. However, thepresent disclosure is not limited thereto, and the planar shape of themain region MA may be a rectangular shape having rounded corners.

The sub-region SBA may protrude from one side of the main region MA inthe second direction DR2. The length of the sub-region SBA in the firstdirection DR1 may be smaller than the length of the main region MA inthe first direction DR1, and the length of the sub-region SBA in thesecond direction DR2 may be smaller than the length of the main regionMA in the second direction DR2, but the present disclosure is notlimited thereto.

Although it is exemplarily shown in FIG. 2 that the sub-region SBA isstretched, the sub-region SBA may be bent and, in this case, arranged onthe bottom surface of the display panel 300. In the case where thesub-region SBA is bent, it may overlap the main region MA in thethickness direction DR3 of the substrate SUB. The display circuit board310 and the display driving circuit 320 may be disposed in thesub-region SBA.

The display circuit board 310 may be attached to one end of thesub-region SBA of the display panel 300 with a conductive adhesivemember such as an anisotropic conductive film. As a consequence, thedisplay circuit board 310 may be electrically connected to the displaypanel 300 and the display driving circuit 320. The display panel 300 andthe display driving circuit 320 may receive digital video data, timingsignals, and driving voltages via the display circuit board 310. Thedisplay circuit board 310 may be a flexible printed circuit board, aprinted circuit board, or a flexible film such as a chip on film.

The display driving circuit 320 may generate signals and voltages fordriving the display panel 300. The display driving circuit 320 may beformed as an integrated circuit (IC) and attached to the sub-region SBAof the display panel 300 by a chip on glass (COG) method, a chip onplastic (COP) method, or an ultrasonic bonding method, but the presentdisclosure is not limited thereto. For example, the display drivingcircuit 320 may be attached to the display circuit board 310 by a chipon film (COF) method.

A touch driving circuit 330 may be disposed on the display circuit board310. The touch driving circuit 330 may be formed as an integratedcircuit and attached to the top surface of the display circuit board310.

Further, a power supply unit may be additionally disposed on the displaycircuit board 310 to supply display driving voltages for driving thedisplay driving circuit 320.

The fingerprint sensor 400 may be disposed on the bottom surface of thedisplay panel 300. The fingerprint sensor 400 may be attached to thebottom surface of the display panel 300 using a fifth bonding member tobe described later. For example, the fifth bonding member may be atransparent adhesive resin such as optically clear resin (OCR).

The bracket 600 may be disposed under the display panel 300. The bracket600 may include or may be formed of plastic, metal, or both plastic andmetal. A first camera hole CMH1 into which a first camera sensor 720 isinserted, a battery hole BH in which a battery is disposed, and a cablehole CAH through which a cable 314 connected to the display circuitboard 310 passes may be formed in the bracket 600.

The main circuit board 700 and a battery 790 may be disposed under thebracket 600. The main circuit board 700 may be a printed circuit boardor a flexible printed circuit board.

The main circuit board 700 may include a main processor 710, a firstcamera sensor 720, and a main connector 730. The first camera sensor 720may be disposed on both the top and bottom surfaces of the main circuitboard 700, the main processor 710 may be disposed on the top surface ofthe main circuit board 700, and the main connector 730 may be disposedon the bottom surface of the main circuit board 700.

The main processor 710 may control all functions of the display device10. For example, the main processor 710 may output digital video data tothe display driving circuit 320 through the display circuit board 310such that the display panel 300 displays an image. Further, the mainprocessor 710 may receive touch data from the touch driving circuit 330and determine the user's touch coordinates, and then execute anapplication indicated by an icon displayed on the user's touchcoordinates. Furthermore, the main processor 710 may convert first imagedata inputted from the first camera sensor 720 into digital video dataand outputs it to the display driving circuit 320 through the displaycircuit board 310, thereby displaying an image captured by the firstcamera sensor 720 on the display panel 300.

The first camera sensor 720 may process an image frame of a still imageor video obtained by the image sensor and output it to the mainprocessor 710. The first camera sensor 720 may be a complementarymetal-oxide-semiconductor (CMOS) image sensor or a charge-coupled device(CCD) sensor. The first camera sensor 720 may be exposed to the bottomsurface of the lower cover 900 by a second camera hole CMH2 to therebycapture an image of a background or an object disposed below the displaydevice 10.

The cable 314 passing through the cable hole CAH of the bracket 600 maybe connected to the main connector 730. Thus, the main circuit board 700may be electrically connected to the display circuit board 310.

The battery 790 may be disposed so as not to overlap the main circuitboard 700 in the third direction DR3. The battery 790 may overlap thebattery hole BH of the bracket 600. In addition, the fingerprint sensor400 may also overlap the battery hole BH of the bracket 600.

The main circuit board 700 may be further equipped with a mobilecommunication module capable of transmitting and receiving radio signalswith at least one of a base station, an external terminal, and a serverin a mobile communication network. The radio signal may include varioustypes of data according to transmission and reception of a voice signal,a video call signal, or a text/multimedia message.

The lower cover 900 may be disposed below the main circuit board 700 andthe battery 790. The lower cover 900 may be fixed by being fastened tothe bracket 600. The lower cover 900 may form an external appearance ofthe bottom surface of the display device 10. The lower cover 900 mayinclude or may be formed of plastic, metal, or both plastic and metal.

The second camera hole CMH2 exposing the bottom surface of the firstcamera sensor 720 may be formed in the lower cover 900. The position ofthe first camera sensor 720 and the positions of the first and secondcamera holes CMH1 and CMH2 corresponding to the first camera sensor 720are not limited to the embodiment illustrated in FIG. 2.

FIG. 3 is a plan view illustrating a display panel, a display circuitboard, and a display driving circuit of FIG. 2.

Referring to FIG. 3, a folding area FA and non-folding areas NFA1 andNFA2 may be further defined in the display device. The folding area FAmay have a line shape extending along the first direction DR1. The firstnon-folding area NFA1 may be located on one side of the folding area FAin the second direction DR2, and the second non-folding area NFA2 may belocated on the other side of the folding area FA in the second directionDR2. The area of each of the non-folding areas NFA1 and NFA2 may belarger than the area of the folding area FA, but is not limited thereto.

The display device may be a foldable display device that may be foldedand unfolded with respect to the folding area FA in a state where thenon-folding areas NFA1 and NFA2 are unfolded. The display device is anin-foldable display device which is in-folded such that the top surfaceof the first non-folding area NFA1 of the display device and the topsurface of the second non-folding area NFA2 of the display device faceeach other with respect to the folding area FA, or an out-foldabledisplay device which is out-folded such that the bottom surface of thefirst non-folding area NFA1 of the display device and the bottom surfaceof the second non-folding area NFA2 of the display device face eachother with respect to the folding area FA.

The fingerprint sensor 400 may be disposed in the second non-foldingarea NFA2, as illustrated in FIG. 3. However, the present disclosure isnot limited thereto, and the fingerprint sensor 400 may be disposed inthe first non-folding area NFA1 or in the folding area FA.

FIG. 4 is an exemplary cross-sectional view of the display panel of FIG.3.

Referring to FIG. 4, the display panel 300 may include display pixelsfor displaying an image. Each of the display pixels SP may include alight emitting element LEL, a first thin film transistor ST1, and acapacitor CAP.

The display substrate DSUB may be made of an insulating material such asglass, or polymer resin. For example, the display substrate DSUB mayinclude or may be formed of polyimide. The display substrate DSUB may bea flexible substrate which can be bent, folded or rolled.

The display substrate DSUB may include, for example, a plurality oforganic layers and a plurality of inorganic layers. For example, thedisplay substrate DSUB may include a first organic layer, a firstbarrier layer disposed on the first organic layer and including at leastone inorganic layer, a second organic layer disposed on the firstbarrier layer, and a second barrier layer disposed on the second organiclayer and including at least one inorganic layer.

A first buffer layer BF1 may be disposed on the display substrate DSUB.The first buffer layer BF1 is a layer for protecting thin filmtransistors of the thin film transistor layer TFTL and a light emittinglayer 172 of the light emitting element layer EML from moisturepermeating through the display substrate DSUB which is susceptible tomoisture permeation. The first buffer layer BF1 may be formed of aplurality of inorganic layers that are alternately stacked. For example,the first buffer layer BF1 may be formed of multiple layers in which oneor more inorganic layers of a silicon nitride layer, a siliconoxynitride layer, a silicon oxide layer, a titanium oxide layer and analuminum oxide layer are alternately stacked.

A first active layer ACT1, a first source electrode S1, and a firstdrain electrode D1 of the first thin film transistor ST1 may be disposedon the first buffer layer BF1. The first active layer ACT1 of the firstthin film transistor ST1 includes polycrystalline silicon,monocrystalline silicon, low-temperature polycrystalline silicon,amorphous silicon, or an oxide semiconductor. The first source electrodeS1 and the first drain electrode D1 may have conductivity by doping asilicon semiconductor or an oxide semiconductor with ions or impurities.The first active layer ACT1 overlaps a first gate electrode G1 in thethird direction DR3 which is the thickness direction of the displaysubstrate DSUB, and the first source electrode S1 and the first drainelectrode D1 may not overlap the first gate electrode G1 in the thirddirection DR3.

A first gate insulating layer GI1 may be disposed on the first activelayer ACT1 of the first thin film transistor ST1. The first gateinsulating layer GI1 may be formed of an inorganic layer, for example, asilicon nitride layer, a silicon oxynitride layer, a silicon oxidelayer, a titanium oxide layer, or an aluminum oxide layer.

A scan line SL, a first capacitor electrode CAE1, and a first gateelectrode G1 of the first thin film transistor ST1 may be disposed onthe first gate insulating layer GIL The first gate electrode G1 mayoverlap the first active layer ACT1 in the third direction DR3. The scanline SL may be electrically connected to the first gate electrode G1.The first capacitor electrode CAE1 may overlap a second capacitorelectrode CAE2 in the third direction DR3. The first gate electrode G1and the scan line SL may be formed as a single layer or multiple layersmade of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold(Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or analloy thereof.

A first interlayer insulating layer 141 may be disposed on the firstgate electrode G1 and the first capacitor electrode CAE1. The firstinterlayer insulating layer 141 may be formed of an inorganic layer, forexample, a silicon nitride layer, a silicon oxynitride layer, a siliconoxide layer, a titanium oxide layer, or an aluminum oxide layer.

The second capacitor electrode CAE2 may be disposed on the firstinterlayer insulating layer 141. Because the first interlayer insulatinglayer 141 has a predetermined dielectric constant, a capacitor CAP maybe formed by the first and second capacitor electrodes CAE1 and CAE2 andthe first interlayer insulating layer 141 disposed between the first andsecond capacitor electrodes CAE1 and CAE2. The second capacitorelectrode CAE2 may be formed as a single layer or multiple layers madeof any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au),titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloythereof.

A second interlayer insulating layer 142 may be disposed on the secondcapacitor electrode CAE2. The second interlayer insulating layer 142 maybe formed of an inorganic layer, for example, a silicon nitride layer, asilicon oxynitride layer, a silicon oxide layer, a titanium oxide layer,or an aluminum oxide layer. The second interlayer insulating layer 142may include may be formed of a plurality of inorganic layers.

A first pixel connection electrode ANDE1 and a data line DL may bedisposed on the second interlayer insulating layer 142. The first pixelconnection electrode ANDE1 may penetrate the first interlayer insulatinglayer 141 and the second interlayer insulating layer 142 to be connectedto the first drain electrode D1 of the first thin film transistor ST1via a first pixel contact hole ANCT1 that exposes the first drainelectrode D1 of the first thin film transistor ST1. The first pixelconnection electrode ANDE1 may be formed as a single layer or multiplelayers made of any one of molybdenum (Mo), aluminum (Al), chromium (Cr),gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) oran alloy thereof.

A first organic layer 160 for planarization may be disposed on the firstpixel connection electrode ANDE1. The first organic layer 160 may beformed of acryl resin, epoxy resin, phenolic resin, polyamide resin,polyimide resin, or the like.

A second pixel connection electrode ANDE2 may be disposed on the firstorganic layer 160. The second pixel connection electrode ANDE2 may beconnected to the first pixel connection electrode ANDE1 via a secondpixel contact hole ANCT2 penetrating the first organic layer 160 toexpose the first pixel connection electrode ANDE1. The second pixelconnection electrode ANDE2 may be formed as a single layer or multiplelayers made of any one of molybdenum (Mo), aluminum (Al), chromium (Cr),gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) oran alloy thereof.

A second organic layer 180 may be disposed on the second pixelconnection electrode ANDE2. The second organic layer 180 may be formedof acryl resin, epoxy resin, phenolic resin, polyamide resin, polyimideresin, or the like.

Meanwhile, in an embodiment, the second pixel connection electrode ANDE2and the second organic layer 180 may be omitted. In this case, the firstpixel connection electrode ANDE1 may be directly connected to a lightemitting pixel electrode 171.

Although FIG. 4 illustrates that the first thin film transistor ST1 isformed by a top gate method in which the first gate electrode G1 islocated above the first active layer ACT1, the present disclosure is notlimited thereto. The first thin film transistor ST1 may be formed by abottom gate method in which the first gate electrode G1 is located belowthe first active layer ACT1, or a double gate method in which the firstgate electrode G1 is located both above and below the first active layerACT1.

The light emitting elements LEL and a bank 190 may be disposed on thesecond organic layer 180. Each of the light emitting elements LELincludes a light emitting pixel electrode 171, a light emitting layer172, and a light emitting common electrode 173.

The light emitting pixel electrode 171 may be formed on the secondorganic layer 180. The light emitting pixel electrode 171 may beconnected to the second pixel connection electrode ANDE2 via a thirdpixel contact hole ANCT3 penetrating the second organic layer 180 toexpose the second pixel connection electrode ANDE2.

In a top emission structure in which light is emitted toward the lightemitting common electrode 173 when viewed with respect to the lightemitting layer 172, the light emitting pixel electrode 171 may be formedof a metal material having high reflectivity to have a stacked structure(Ti/Al/Ti) of aluminum and titanium, a stacked structure (ITO/Al/ITO) ofaluminum and ITO, an APC alloy, and a stacked structure (ITO/APC/ITO) ofan APC alloy and ITO. The APC alloy is an alloy of silver (Ag),palladium (Pd) and copper (Cu).

The bank 190 may be formed to delimit the light emitting pixel electrode171 on the second organic layer 180 to define an emission area EA. Thebank 190 may be formed to cover the edge of the light emitting pixelelectrode 171. The bank 190 may be formed of an organic layer such asacryl resin, epoxy resin, phenolic resin, polyamide resin, polyimideresin and the like.

The emission area EA is an area in which the light emitting pixelelectrode 171, the light emitting layer 172, and the light emittingcommon electrode 173 are sequentially stacked such that the holes fromthe light emitting pixel electrode 171 and the electrons from the lightemitting common electrode 173 are combined with each other to emitlight.

The light emitting layer 172 is formed on the light emitting pixelelectrode 171 and the bank 190. The light emitting layer 172 may includeor may be formed of an organic material to emit light in a predeterminedcolor. For example, the light emitting layer 172 includes a holetransporting layer, an organic material layer, and an electrontransporting layer.

The light emitting common electrode 173 is formed on the light emittinglayer 172. The light emitting common electrode 173 may be formed tocover the light emitting layer 172. The light emitting common electrode173 may be a common layer formed in common on all emission areas EA. Acapping layer may be formed on the light emitting common electrode 173.

In the top emission structure, the light emitting common electrode 173may be formed of transparent conductive oxide (TCE) such as indium tinoxide (ITO) and indium zinc oxide (IZO) capable of transmitting light ora semi-transmissive conductive material such as magnesium (Mg), silver(Ag), or an alloy of magnesium (Mg) and silver (Ag).

An encapsulation layer TFE may be disposed on the light emitting commonelectrode 173. The encapsulation layer TFE includes at least oneinorganic layer to prevent oxygen or moisture from permeating into thelight emitting element layer EML. In addition, the encapsulation layerTFE includes at least one organic layer to protect the light emittingelement layer EML from foreign substances such as dust. For example, theencapsulation layer TFE includes a first encapsulation inorganic layerTFE1, an encapsulation organic layer TFE2, and a second encapsulationinorganic layer TFE3.

FIG. 5 is a cross-sectional view taken along line I-I′ of FIG. 3. FIG. 6is a plan view illustrating a lower metal sheet and a filling memberaccording to an embodiment. FIG. 5 illustrates that a user touches thetop surface of the cover window 100 with a finger F for fingerprintauthentication.

Referring to FIG. 5, the display device may include a polarizing layerPOL, the cover window 100, a metal plate LP, a filling member RL, andbonding members AM1 to AM5 that bond adjacent members.

The polarization layer POL may be disposed on the display panel 300. Thepolarization layer POL may be adhered to the top surface of the displaypanel 300 through the first bonding member AM1. The polarization layerPOL serves to reduce reflection of external light incident through thecover window 100. The first bonding member AM1 may be a transparentadhesive resin such as an optically clear resin (OCR) or a transparentadhesive film such as an optically clear adhesive (OCA) film.

The cover window 100 may be disposed on the top surface of thepolarization layer POL. The cover window 100 may be adhered to the topsurface of the polarization layer POL through the second bonding memberAM2. In some embodiments, the polarization layer POL may be omitted. Insome embodiments where the polarization layer POL is omitted, colorfilters may be disposed between the cover window 100 and the displaypanel 300, and a black matrix may be disposed between adjacent colorfilters. The material of the second bonding member AM2 may be selectedfrom the exemplified materials of the first bonding member AM1.

The protective layer PF may be disposed on the bottom surface of thedisplay panel 300. The protective layer PF may include or may be formedof polyimide (PI), polyethylene terephthalate (PET), or the like, but isnot limited to the exemplified materials. The protective layer PF may beadhered to the bottom surface of the display panel 300 through the thirdbonding member AM3.

The third bonding member AM3 may be a transparent adhesive resin such asan optically clear resin (OCR) or a transparent adhesive film such as anoptically clear adhesive (OCA) film. When the display panel 300according to an embodiment is a front emission type display panel, thelight transmittance of the third bonding member AM3 may be lower thanthe light transmittance of the first and second bonding members AM1 andAM2 described above, but the present disclosure is not limited thereto.

The metal plate LP may be disposed under the protective layer PF. Themetal plate LP may be adhered to the bottom surface of the protectivelayer PF through the fourth bonding member AM4. As shown in FIG. 6, themetal plate LP may include a first metal plate LP1 disposed in the firstnon-folding area NFA1, a second metal plate LP2 disposed in the secondnon-folding area NFA2, and a third metal plate LP3 disposed in thefolding area FA. The third metal plate LP3 may be formed of a pluralityof patterns spaced apart from each other in the second direction DR2.Each of the patterns may extend in the first direction DR1. The firstand second metal plates LP1 and LP2 serve to support the display panel300 thereabove in the non-folding areas NFA1 and NFA2, respectively.Each of the first and second metal plates LP1 and LP2 may have a wholepattern shape such as a plate. The metal plate LP may be made of metalor a metal alloy. For example, the metal plate LP may be made of analuminum alloy or stainless steel (SUS), but the material is not limitedthereto. In some embodiments, the third metal plate LP3 may be omitted.In the drawing, the first to third metal plates LP1, LP2, and LP3 areshown as being spaced apart from each other, but the present disclosureis not limited thereto, and the first to third metal plates LP1, LP2,and LP3 may be integrally formed and combined with each other.

Meanwhile, a through hole PH surrounded by materials forming the secondmetal plate LP2 may be further defined. In an embodiment, the secondmetal plate LP2 may be provided with the through hole PH which extendsfrom a top surface of the second metal plate LP2 to a bottom surface ofthe second metal plate LP2. When the display panel 300 is viewed in aplan view, the through hole PH may be defined by materials forming thesecond metal plate LP2. The through hole PH may completely penetratefrom the top surface of the second metal plate LP2 to the bottom surfaceof the second metal plate LP2 in the thickness direction. The fillingmember RL may be disposed in the through hole PH. When the display panel300 is viewed in a plan view, the filling member RL may be completelysurrounded by the second metal plate LP2. The filling member RL may bebonded to the bottom surface of the protective layer PF through thefourth bonding member AM4 and may be bonded to the fingerprint sensor400 through the fifth bonding member AM5. The fourth bonding member AM4may be selected from the exemplified materials of the third bondingmember AM3 described above. In an embodiment, the filling member RL andthe metal plate LP may be at the same level relative to the protectivelayer PF or the display panel 300.

The fifth bonding member AM5 may also be referred to as a member-sensorbonding member. The fingerprint sensor 400 may be disposed to overlapthe filling member RL in the thickness direction. The fingerprint sensor400 may be bonded to the bottom surface of the filling member RL and thebottom surface of the second metal plate LP2 through the fifth bondingmember AM5. For example, the fifth bonding member AM5 may be atransparent adhesive resin such as optically clear resin (OCR). Theresin may be, for example, an epoxy resin, but is not limited thereto.

As shown in FIG. 5, the finger F with a fingerprint may face and touchthe cover window 100. The fingerprint of the finger F may includedepressions and prominences. The depressions and prominences of thefingerprint may be repeatedly disposed. In at least one sectionincluding one depression and one prominence taken among the repeateddepressions and prominences, the prominence may be referred to as ridgeRID and the depression may be referred to as valley VAL as shown in FIG.7. The ridge RID of the fingerprint may be closer to the cover window100 than the valley VAL of the fingerprint. An operation method of theultrasonic fingerprint sensor will be described in detail with referenceto FIG. 7.

In some embodiments, separate layers may be further disposed between themetal plate LP and the protective layer PF. The layers include at leastone functional layer. The functional layer may be a layer that performsa heat dissipation function, an electromagnetic shielding function, agrounding function, a buffering function, a rigidity enhancing function,a supporting function, and/or a digitizing function.

FIG. 7 is an enlarged cross-sectional view of area A of FIG. 5.

Referring to FIGS. 5 and 7, a first ultrasonic wave IS1 travel to theridge RID and the valley VAL of the fingerprint and then reflected bythe ridge RID and the valley VAL. The first ultrasonic wave IS1travelling toward the ridge RID may pass through the fifth bondingmember AM5, the filling member RL, the fourth bonding member AM4, theprotective layer PF, the third bonding member AM3, the display panel300, the first bonding member AM1, the polarization layer POL, thesecond bonding member AM2, and the cover window 100 to reach the ridgeRID. As shown in FIGS. 5 and 7, because the ridge RID is in directcontact with the cover window 100, no gap, e.g., air gap AG, is presentbetween the ridge RID and the cover window 100. On the other hand, thefirst ultrasonic wave IS1 travelling toward the valley VAL may passthrough the fifth bonding member AM5, the filling member RL, the fourthbonding member AM4, the protective layer PF, the third bonding memberAM3, the display panel 300, the first bonding member AM1, thepolarization layer POL, the second bonding member AM2, the cover window100, and the air gap AG to reach the valley VAL. The first ultrasonicwave IS1 travelling toward the valley VAL may further pass through theair gap AG as compared to the first ultrasonic wave IS1 travellingtoward the ridge RID. With regard to the first ultrasonic wave IS1emitted by the ultrasonic fingerprint sensor 400, the first ultrasonicwave IS1 travelling to the ridge RID may be reflected by the ridge RIDof the finger F as a first signal RS1. Further, the first ultrasonicwave IS1 travelling toward the valley VAL may be reflected by aninterface between the air gap AG and the cover window 100 as a firstreflection signal RS11, and the first ultrasonic wave IS1 travelling tothe valley VAL may be reflected by valley VAL of the finger F as asecond reflection signal RS12. The first and second reflection signalsRS11 and RS12 constituting the first signal RS1. The magnitude of thefirst reflection signal RS11 may be greater than that of the secondreflection signal RS12.

The ultrasonic fingerprint sensor 400 may recognize the ridge RID andthe valley VAL based on a first time difference between an emission timepoint of the first ultrasonic wave IS1 and an arrival time point of thefirst signal RS1 reflected by the ridge RID and a second time differencebetween the emission time point of the first ultrasonic wave IS1 and anarrival time point of the first signal RS1 reflected by the valley VALand the interface between the air gap AG and the cover window 100.However, given the existence of the air gap AG between the valley VALand the cover window 100 and the ultrasonic wave propagation speedvarying with medium, the ridge RID and the valley VAL may be difficultto be distinguished from each other.

To factor in the air gap AG between the valley VAL and the cover window100 for more accurate distinction between the ridge RID and the valleyVAL, a ratio between the strength of the first ultrasonic wave IS1 andthe strength of the first signal RS1 may be calculated to distinguishthe ridge RID and the valley VAL from each other. The ratio of thestrength of the first signal RS1 to the strength of the first ultrasonicwave IS1 is defined as reflection coefficient. The reflectioncoefficient of the first ultrasonic wave IS1 irradiated to the valleyVAL may be greater than the reflection coefficient of the firstultrasonic wave IS1 irradiated to the ridge RID. Whether it is the ridgeRID or the valley VAL may be determined based on the reflectioncoefficient of the first ultrasonic wave IS1.

Referring back to FIG. 5, if the metal plate LP is disposed on thetravelling path of the first ultrasonic wave IS1 emitted upward from thefingerprint sensor 400 and/or the first signal RS1 reflected from thefingerprint of the finger F, the signal strength of each of the firstultrasonic waves IS1 and the signal strength of the first signal RS1 maybe reduced. In the display device according to an embodiment, the metalplate LP is cut to form a through hole PH which extends from the topsurface of the metal plate LP to the bottom surface of the metal plateLP. The through hole PH may be located in the travelling path of thefirst ultrasonic wave IS1, and thus the signal strength of each of thefirst ultrasonic waves IS1 and the signal strength of the first signalRS1 is not reduced by the first metal plate LP.

Meanwhile, when the fingerprint sensor 400 is directly attached to theprotective layer PF through the fourth bonding member AM4 in the throughhole PH, due to an attachment pressure, the display panel 300 and thelike overlapping the fingerprint sensor 400 in the thickness directionmay be partially pressed in the upward direction, and the pressing maybe visually recognized from the outside, causing a display failure. Toavoid the pressing, when the fingerprint sensor 400 is attached to thebottom surface of the second metal plate LP2 adjacent to the throughhole PH with the through hole PH interposed therebetween, the firstultrasonic wave IS1 emitted from the fingerprint sensor 400 may besubject to signal distortion due to the air gap in the through hole PH.

As a comparative example, a bonding member may fill the through hole PHand is attached to the bottom surface of the protective layer PF, andthe fingerprint sensor 400 may be bonded through the bonding memberfilling the through hole PH to the protective layer PF. The protectivelayer PF and/or the display panel 300 may be pressed due to aninsufficient hardness of the bonding member in such attachment process,and thus the failure due to the pressing arising from the attachmentpressure still occurs.

In the display device according to an embodiment, the inside of thethrough hole PH is filled with the filling member RL having a muchgreater hardness than the fifth bonding member AM5, and the fingerprintsensor 400 is attached to the bottom surface of the filling member RLthrough the fifth bonding member AM5, thereby preventing defectivepressing of the protective layer PF and/or the display panel 300, andvisual recognition of the through hole PH. From the viewpoint ofpreventing defective pressing, the hardness of the filling member RL maybe about 10 times or more the hardness of the fifth bonding member AM5.In an embodiment, the hardness of the filling member RL may be 20 timesor 30 times or more the hardness of the fifth bonding member AM5. Forexample, the hardness of the filling member RL may be 0.8 Gps or more,but is not limited thereto. The filling member RL may include materialswhich fills the through hole PH. For example, the filling member RL mayinclude or may be formed of a material that fills the through hole PH byan injection method or an adhesion method. The filling member RL may bemade of acrylonitrile butadiene styrene copolymer (ABS), polycarbonate(PC), or the like, although not limited thereto. The hardness of thefilling member RL may be smaller than that of the adjacent second metalplate LP2.

The filling member RL is located on the path of the first ultrasonicwave IS1 emitted from the fingerprint sensor 400, and the firstultrasonic wave IS1 may have a frequency band in which the ultrasonicwave is allowed to easily pass through the display panel 300. Toincrease the sensing efficiency of the fingerprint sensor 400, thefilling member RL may have an impedance similar to that of the displaypanel 300. For example, the impedance of the filling member RL may beset within an error of about 5 MPa*m/s*10{circumflex over ( )}-6 of theimpedance of the display panel 300.

In some other embodiments, when the ultrasonic fingerprint sensor isapplied, the filling member RL may further include a black colorant.Since the filling member RL further includes a black colorant, it ispossible to prevent the fingerprint sensor 400 from being visuallyrecognized from the outside.

When the optical fingerprint sensor is applied as the fingerprint sensor400, the filling member RL may have the same hardness and material asthe filling member RL when the ultrasonic fingerprint sensor is applied.However, since the optical fingerprint sensor recognizes a fingerprintthrough light, the filling member RL may be designed in consideration ofthe transmittance of the corresponding light. When the opticalfingerprint sensor is applied, the filling member RL may have atransmittance of about 90% or more for the light. The light may includevisible light, ultraviolet light, or infrared light.

FIG. 8 is an enlarged cross-sectional view of area B of FIG. 5.

Referring to FIG. 8, a top surface RLb of the filling member RL may bein direct contact with the fourth bonding member AM4, a bottom surfaceRLa of the filling member RL may be in direct contact with the fifthbonding member AM5, and a side surface RLs of the filling member RL maybe in direct contact with a side surface LP2 of the second metal plateLP2. The bottom surface RLa of the filling member RL may protrudefurther downward beyond a bottom surface LP2 a of the second metal plateLP2, and the filling member RL may partially cover the bottom surfaceLP2 a of the second metal plate LP2. A width W1 of the filling member RLprotruding further downward beyond the bottom surface LP2 a of thesecond metal plate LP2 may be greater than a width W1 of the fillingmember RL overlapping the second metal plate LP2 in the horizontaldirection (second direction DR2 in FIG. 3). A thickness h2 of thefilling member RL may be greater than a thickness h1 of the adjacentsecond metal plate LP2. The width W1 of the filling member RL protrudingfurther downward beyond the bottom surface LP2 a of the second metalplate LP2 of the filling member RL may be larger than the width of thethrough hole PH.

The fifth bonding member AM5 may be in direct contact with the entirebottom surface RLa of the filling member RL, the side surface of thefilling member RL protruding further downward beyond the bottom surfaceLP2 a of the second metal plate LP2, and a part of the bottom surfaceLP2 a of the second metal plate LP2. A side surface AM5 s of the fifthbonding member AM5 may be located outside the side surface of thefilling member RL protruding further downward beyond the bottom surfaceLP2 a of the second metal plate LP2, and a width W2 of the fifth bondingmember AM5 may be larger than the width W1 of the filling member RL. Asin the above-described embodiment, the fifth bonding member AM5 is incontact with the entire bottom surface RLa of the filling member RL andalso is in contact with a part of the bottom surface LP2 a of the secondmetal plate LP2. Accordingly, the second metal plate LP2 and the fillingmember RL are indirectly bonded through the fifth bonding member AM5.Thus, it is possible to prevent the filling member RL from escaping fromthe through hole PH, thereby enhancing the durability of the displaydevice.

The fingerprint sensor 400 includes an active area SA through whichultrasonic waves are emitted or received, and an inactive area NSAthrough which no ultrasonic waves are emitted or received. The width W1of the filling member RL may be larger than a width WSA of the activearea SA. A width W3 of the fingerprint sensor 400 may be smaller thanthe width W2 of the fifth bonding member AM5.

As in the above-described embodiment, a structure in which the fillingmember RL partially covers and contacts the bottom surface of the secondmetal plate LP2 may be formed in a process of forming the filling memberRL in the through hole PH of the second metal plate LP2.

FIG. 9 is a cross-sectional view showing a modified example of thefilling member of FIG. 8.

Referring to FIG. 9, the width W1 of the filling member RL may have aconstant value in the thickness direction. The thickness h2 of thefilling member RL may be the same as the thickness h1 of the adjacentsecond metal plate LP2. The bottom surface RLa of the filling member RLand the bottom surface LP2 a of the second metal plate LP2 may belocated on the same line at the same height from the bottom surface ofthe fourth bonding member AM4.

FIG. 10 is a cross-sectional view showing a modified example of thefilling member of FIG. 8.

FIG. 10 illustrates that the bottom surface LP2 a of the second metalplate LP2 protrudes further downward than the bottom surface RLa of thefilling member RL, and the thickness h2 of the filling member RL may besmaller than the thickness h1 of the second metal plate LP2.

FIG. 11 is a cross-sectional view showing a modified example of thefilling member of FIG. 8. FIG. 12 is a cross-sectional view showing amodified example of the filling member of FIG. 8.

In the modified examples of the filling member RL of FIGS. 11 and 12,the width of the filling member RL may be differently applied accordingto the thickness direction to prevent the filling member RL fromescaping from (or falling off) the through hole PH.

Referring to FIG. 11, each of a width W1 of the top surface RLb of thefilling member RL in contact with the fourth bonding member AM4 and awidth W1 of the bottom surface RLa of the filling member RL in contactwith the fifth bonding member AM5 may be smaller than a width W4 of anintermediate surface positioned between the top surface RLb and thebottom surface RLa of the filling member RL. The intermediate surfacemay be located at an intermediate point in the thickness directionbetween the top surface RLb and the bottom surface RLa.

An upper side surface RLsa of the filling member RL in contact with anupper side surface LP2 sa of the second metal plate LP2 and a lower sidesurface RLsb of the filling member RL in contact with a lower sidesurface LP2 sb of the second metal plate LP2 may have different slopes.The upper side surface RLsa of the filling member RL positioned on theleft may extend in a left-downward direction from a top surface RL3 bthereof, and the lower side surface RLsb of the filling member RLpositioned on the left may extend in a left-upward direction from abottom surface RL3 a thereof. The upper side surface LP2 sa and thelower side surface LP2 sb of the second metal plate LP2 may have shapescorresponding to the upper side surface RLsa and the lower side surfaceRLsb of the filling member RL in contact therewith, respectively. In thepresent embodiment, the width of the through hole PH may increase andthen decrease from the top to the bottom.

In accordance with the filling member RL according to the presentmodified example, the filling member RL is disposed to overlap the lowerside surface LP2 sb of the second metal plate LP2 in the thicknessdirection while increasing the contact area between the upper sidesurface RLsa and the upper side surface LP2 sa of the second metal plateLP2 and the contact area between the lower side surface RLsb and thelower side surface LP2 sb of the second metal plate LP2. Accordingly, itis possible to prevent the filling member RL from escaping from thethrough hole PH, thereby improving the reliability of the displaydevice.

On the contrary, according to the filling member RL of FIG. 12, shapesof the upper side surface RLsa and the lower side surface RLsb may besymmetrical with respect to an imaginary line connecting a contact pointbetween the upper side surface RLsa and the fourth bonding member AM4and a contact point between the lower side surface RLsb and the fifthbonding member AM5. In the present embodiment, the width of the throughhole PH may decrease and then increase from the top to the bottom.

FIG. 13 is a cross-sectional view illustrating a partial area of across-sectional view of a display device according to anotherembodiment.

Referring to FIG. 13, the present embodiment is different from thedisplay device of FIG. 8 in that the side surface RLs of the fillingmember RL and the side surface LP2 s of the second metal plate LP2 maybe bonded through a separate ninth bonding member AM9.

The type of the ninth bonding member AM9 may be one of the exemplifiedtypes of the first bonding member AM1 described above, but is notlimited thereto, and may be a double-sided tape. Since the side surfaceRLs of the filling member RL and the side surfaces LP2 s of the secondmetal plate LP2 are bonded through the separate ninth bonding memberAM9, it is possible to increase a bonding force between the fillingmember RL and the second metal plate LP2, thereby preventing the fillingmember RL from escaping from the through hole PH.

FIG. 14 is a cross-sectional view showing a modified example of thefilling member of FIG. 8.

Referring to FIG. 14, it is different from the filling member RL of FIG.8 in that the side surface RLs of the filling member RL is inclineddownward from the top surface RLb to the bottom surface RLa. Thecross-sectional shape of the filling member RL according to the presentembodiment may be an inverted trapezoid. In the present embodiment, thewidth of the through hole PH may decrease from the top to the bottom.According to the present embodiment, the contact area between the sidesurface RLs of the filling member RL and the side surface LP2 s of theadjacent second metal plate LP2 can be increased, thereby preventing thefilling member RL from escaping from the through hole PH.

FIG. 15 is a cross-sectional view showing a modified example of thefilling member of FIG. 8.

Referring to FIG. 15, it is different from the filling member RL of FIG.8 in that the width W1 of the filling member RL is larger than the widthW3 of the fingerprint sensor 400. According to the present embodiment,the filling member RL is not only larger than the width WSA of theactive area SA, but also covers the inactive area NSA, so thatultrasonic waves transmitted from the active area SA can be providedmore efficiently.

FIG. 16 is a cross-sectional view of a display device according to stillanother embodiment.

Referring to FIG. 16, the present embodiment is different from the metalplate LP of FIG. 5 in that a metal plate LP_1 is integrally formed.Unlike the metal plate LP of FIG. 5, the metal plate LP_1 according tothe present embodiment may be formed in a whole shape in all areas. Inreduce the stress of the metal plate LP in the folding area FA, which iscaused by folding, the metal plate LP_1 according to the presentembodiment may generally have a thickness smaller than that of the metalplate LP shown in FIG. 5. Alternatively, unlike FIG. 16, the thicknessof the metal plate LP_1 in the folding area FA may be formed to bethinner than the thickness of the metal plate LP_1 in the adjacentnon-folding areas NFA1 and NFA2.

In some embodiments, separate layers may be further disposed between themetal plate LP_1 and the protective layer PF. The layers include atleast one functional layer. The functional layer may be a layer thatperforms a heat dissipation function, an electromagnetic shieldingfunction, a grounding function, a buffering function, a rigidityenhancing function, a supporting function, and/or a digitizing function.

FIG. 17 is a cross-sectional view of a display device according to stillanother embodiment. FIG. 18 is a plan view illustrating a lower panelsheet and a display panel of FIG. 17.

Referring to FIGS. 17 and 18, a display device according to the presentembodiment is different from the display device according to FIG. 5 inthat a lower panel sheet 500 may be disposed on the bottom surface ofthe metal plate LP_1.

More specifically, the metal plate LP_1 may be disposed between thelower panel sheet 500 and the display panel 300. The lower panel sheet500 may include a sheet hole H completely penetrating from the topsurface to the bottom surface of the lower panel sheet 500 in a regionoverlapping the fingerprint sensor 400 in the thickness direction. Thefingerprint sensor 400 may be bonded to the bottom surface of thefilling member RL through the fifth bonding member AM5 in the sheet holeH. When the display device 10 is viewed in a plan view, the sheet hole Hmay be completely surrounded by materials forming a lower panel sheet500_2.

The lower panel sheet 500 includes at least one functional layer. Thefunctional layer may be a layer that performs a heat dissipationfunction, an electromagnetic shielding function, a grounding function, abuffering function, a rigidity enhancing function, a supportingfunction, and/or a digitizing function. The functional layer may be asheet layer, a film layer, a thin layer, a coating layer, a panel, aplate, or the like. One functional layer may consist of a single layeror a stack of multiple thin films or coating layers. The functionallayer may be, for example, a supporting member, a heat dissipationlayer, an electromagnetic shielding layer, an impact absorbing layer, adigitizer, or the like. In an embodiment, the lower panel sheet 500 mayinclude an impact absorbing layer. In some embodiments, the lower panelsheet 500 may include an impact absorbing layer (or cushion layer) and aheat dissipation layer. In some other embodiments, the lower panel sheet500 may include two functional layers selected from a supporting member,a heat dissipation layer, an embossed layer, an electromagneticshielding layer, an impact absorbing layer, and a digitizer as describedabove, or three or more functional layers.

In some other embodiments, separate layers may be further disposedbetween the metal plate LP and the protective layer PF. The layers maybe at least one of the exemplified functional layers of the lower panelsheet 500 described above.

FIG. 19 is a cross-sectional view of a display device according to stillanother embodiment.

Referring to FIG. 19, the display device according to the presentembodiment is different from the display device according to FIG. 18 inthat a lower panel sheet 500_1 is disposed only on one side of thefingerprint sensor 400 and is not disposed on the other side opposite tothe one side.

FIG. 20 is a plan view of a display device according to still anotherembodiment. FIG. 21 is a cross-sectional view of a part of a mainregion, a bending region, and a part of a sub-region of FIG. 20.

The display device of FIGS. 20 and 21 is different from the displaydevice of FIGS. 1 to 8 in that the display device of the FIGS. 20 and 21is not foldable, and does not include a metal plate. In the descriptionof the display device of FIGS. 20 and 21, a redundant description of thecontents described with reference to FIGS. 1 to 8 will be omitted exceptfor portions that are different from those described with reference toFIGS. 1 to 8.

Referring to FIGS. 20 and 21, a display panel 300_1 according to thepresent embodiment may be a panel that has a folded state in the bendingregion BA unlike the display panel 300 of FIGS. 1 to 8 in whichfolding/non-folding is freely performed.

As illustrated in FIG. 21, the protective layer PF may be disposed onthe bottom surface of the display panel 300_1 in the main region MA andthe sub-region SBA, and may not be disposed in the bending region BA. Inan embodiment, a portion of the display panel 300_1 in the main regionMA may vertically overlap a portion of the display panel 300_1 in thesub-region SBA. For example, the main region MA may vertically overlapthe sub-region SBA. The term “vertically” may refer to a thicknessdirection of the display device. The display device having the displaypanel 300_1 may be in the folded state in the final product, and suchoverlapping may increase the thickness of the display device, but reducethe width of the display device.

A filling member RL_1 may be bonded to the bottom surface of theprotective layer PF in the main region MA. The filling member RL_1 maybe disposed over the whole surface of the bottom surface of theprotective layer PF. The filling member RL_1 may not be disposed in thebending region BA. The lower panel sheet 500 may be disposed on thebottom surface of the filling member RL_1. The lower panel sheet 500 maybe disposed in the main region MA except for the sheet hole H, and maynot be disposed in the bending region BA. In an embodiment, the lowerpanel sheet 500 may be provided with the sheet hole H which exposes thebottom surface of the filling member RL_1. In the sub-region SBA, aspacer TP is interposed between the lower panel sheet 500 and theprotective layer PF to compensate for a level difference. The other sidesurfaces of the spacer TP and of the third bonding member AM3 may bealigned at the end of the sub-region SBA. One end of the display circuitboard 310 may be attached to one surface of the display panel 300_1 andthe other end thereof may be attached to the bottom surface of the lowerpanel sheet 500.

According to the present embodiment, the filling member RL_1 having ahigher strength (e.g., a hardness) than the fifth bonding member AM5 islocated between the fingerprint sensor 400 and the display panel 300_1,so that the display panel 300_1 may be prevented from being pressed whenthe fingerprint sensor 400 is attached.

FIG. 22 is a cross-sectional view of a display device according to stillanother embodiment.

Referring to FIG. 22, it is different from the display device of FIG. 21in that a filling member RL_2 may have a portion, with a thickness h3,overlapping the fingerprint sensor 400 in the thickness direction. Thethickness h3 of the portion of the filling member RL_2 may be differentfrom that of the other portion of the filling member RL_2. For example,the thickness h3 of the portion of the filling member RL_2 b overlappingthe fingerprint sensor 400 may be greater than a thickness h2 of theother portion of the filling member RL_2 a which does not overlap thefingerprint sensor 400. In some embodiments, the thickness h3 of thefilling member RL_2 overlapping the fingerprint sensor 400 may besmaller than the thickness h2 of the filling member RL_2 not overlappingthe fingerprint sensor 400.

FIG. 23 is a cross-sectional view of a display device according to stillanother embodiment.

Referring to FIG. 23, the display device according to the presentembodiment is different from the display device of FIG. 21 in that afilling member RL_3 is not disposed on the entire surface of the mainregion MA, and is disposed only in a region overlapping the fingerprintsensor 400.

The sheet hole H of the lower panel sheet 500_2 may have a width smallerthan that of the filling member RL_3. Accordingly, a part of the lowerpanel sheet 500_2 may overlap the filling member RL_3 in the thicknessdirection, and the remaining parts that do not overlap the fillingmember RL_3 may cover the side surface of the filling member RL_3 whileconformally reflecting a step due to the filling member RL_3, as shownin FIG. 23, and may be bonded to the bottom of the display panel 300_1(if there is a separate bonding member between the display panel 300_1and the filling member RL_3, the remaining parts being adhered to thebonding member).

FIG. 24 is a cross-sectional view of a display device according to stillanother embodiment.

Referring to FIG. 24, in the display device according to the presentembodiment, the lower panel sheet 500 may be bonded to the bottom of thedisplay panel 300_1, and a sheet hole H of the lower panel sheet 500 mayhave a width larger than that of the filling member RL_3. The lowerpanel sheet 500 may not overlap the filling member RL_3 in the thicknessdirection. As shown in FIG. 24, the filling member RL_3 and the lowerpanel sheet 500 may be spaced apart from each other with a predeterminedgap, and a resin R may be further disposed in the gap. The resin Rserves as a member-inner surface bonding member for bonding a sidesurface (or inner side surface) of the lower panel sheet 500 and a sidesurface of the filling member RL_3, which are spaced apart from eachother. In accordance with the display device according to the presentembodiment, since the resin R is further disposed in the gap between thefilling member RL_3 and the lower panel sheet 500, the gap may beprevented from being visually recognized from the outside.

Although embodiments of the invention have been disclosed forillustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

What is claimed is:
 1. A display device comprising: a display panel; ametal plate disposed on a bottom surface of the display panel andconfigured to support the display panel; a filling member disposed onthe bottom surface of the display panel, wherein the filling member isdisposed on the same level as the metal plate relative to the bottomsurface of the display panel, and and wherein a material of the metalplate is different from a material of the filling member; a fingerprintsensor disposed on a bottom surface of the filling member; and amember-sensor bonding member disposed between the fingerprint sensor andthe filling member to bond the fingerprint sensor to the filling member,wherein a hardness of the filling member is greater than a hardness ofthe member-sensor bonding member.
 2. The display device of claim 1,wherein the filling member and the metal plate are in direct contactwith each other.
 3. The display device of claim 1, wherein the hardnessof the filling member is 10 times or more the hardness of themember-sensor bonding member, and wherein a hardness of the metal plateis greater than the hardness of the filling member.
 4. The displaydevice of claim 1, wherein the metal plate is provided with a throughhole extending from a top surface of the metal plate to a bottom surfaceof the metal plate, and wherein the filling member fills the throughhole.
 5. The display device of claim 4, wherein a width of the throughhole decreases from the top surface of the metal plate to the bottomsurface of the metal plate.
 6. The display device of claim 4, wherein awidth of the through hole decreases from the top surface of the metalplate to a first point of the through hole which is disposed between thetop surface of the metal plate and the bottom surface of the metal plateand then increases from the first point to the bottom surface.
 7. Thedisplay device of claim 4, wherein a width of the through hole increasesfrom the top surface of the metal plate to a first point of the throughhole which is disposed between the top surface of the metal plate andthe bottom surface of the metal plate and then decreases from the firstpoint to the bottom surface.
 8. The display device of claim 1, whereinthe fingerprint sensor includes an ultrasonic fingerprint sensor, andwherein the ultrasonic fingerprint sensor is configured to compare anincident ultrasonic wave which is transmitted upward from the ultrasonicfingerprint sensor with a fingerprint reflection ultrasonic wave whichis reflected from a finger on a top surface of the display panel, whichis opposite to the bottom surface thereof, and recognize fingerprint ofthe finger.
 9. The display device of claim 1, wherein the fingerprintsensor includes an optical fingerprint sensor, and wherein the fillingmember has a transmittance of 90% or more for light from the opticalfingerprint sensor.
 10. The display device of claim 1, wherein a widthof the member-sensor bonding member is larger than a width of thefilling member, and wherein the member-sensor bonding member is indirect contact with a bottom surface of the metal plate.
 11. The displaydevice of claim 1, wherein a thickness of the filling member is greaterthan a thickness of the metal plate, and wherein the filling memberpartially covers a bottom surface of the metal plate.
 12. The displaydevice of claim 1, wherein when the display device is viewed in a planview, the filling member is completely surrounded by the metal plate.13. The display device of claim 1, wherein a folding area extending in afirst direction, a first non-folding area disposed on a first side ofthe folding area, and a second non-folding area disposed on a secondside of the folding area are defined in the display device, wherein thefirst non-folding area, the folding area, and the second non-foldingarea are arranged in a second direction different from the firstdirection, and wherein the display device is folded with respect to thefolding area.
 14. The display device of claim 1, further comprising: alower panel sheet disposed on a bottom surface of the metal platewithout vertically overlapping the fingerprint sensor.
 15. The displaydevice of claim 14, wherein the lower panel sheet includes a cushionlayer, wherein the cushion layer includes a sheet hole completelypenetrating from a top surface of the cushion layer to a bottom surfaceof the cushion layer, and wherein the fingerprint sensor is disposed inthe sheet hole.
 16. The display device of claim 14, wherein when thedisplay device is viewed in a plan view, the lower panel sheet isdisposed on a first side of the fingerprint sensor without beingdisposed on a second side, which is opposite to the first side of thefingerprint sensor.
 17. A display device comprising: a display panel inwhich a main region, a sub-region having an area smaller than that ofthe main region, and a bending region are defined, the bending regionbeing disposed between the main region and the sub-region, and a portionof the display panel in the main region and a portion of display panelin the sub-region overlapping each other in a thickness direction of thedisplay device; a filling member disposed on a first surface of thedisplay panel in the main region; a lower panel sheet disposed on afirst surface of the filling member in the main region and on the firstsurface of the display panel in the main region, the lower panel sheetbeing provided with a sheet hole penetrating the lower panel sheet inthe thickness direction of the display device; a fingerprint sensordisposed on the first surface of the filling member in the main region;and a member-sensor bonding member disposed between the fingerprintsensor and the first surface of the filling member to bond thefingerprint sensor to the filling member, wherein the sheet hole of thelower panel sheet exposes an inner side surface of the lower panelsheet, wherein the fingerprint sensor overlaps, in the thicknessdirection of the display device, a first region defined by the sheethole, and wherein a hardness of the filling member is greater than ahardness of the member-sensor bonding member.
 18. The display device ofclaim 17, wherein the filling member includes a first portionoverlapping the first region defined by the sheet hole, and a secondportion outside the first region, and wherein a thickness of the firstportion of the filling member is greater than a thickness of the secondportion of the filling member.
 19. The display device of claim 17,wherein a width of the filling member is larger than a width of thesheet hole, wherein the lower panel sheet covers a first side surface ofthe filling member and a second side surface of the filling member, andwherein the first side surface of the filling member and the second sidesurface of the filling member are opposite to each other.
 20. Thedisplay device of claim 17, wherein a width of the filling member issmaller than a width of the sheet hole, wherein the filling member isdisposed in the sheet hole, wherein the exposed inner side surface ofthe lower panel sheet is spaced apart from a side surface of the fillingmember, and wherein a member-inner surface bonding member is disposed ina gap between the filling member and the inner side surface of the lowerpanel sheet to bond the filling member to the exposed inner side surfaceof the lower panel sheet.
 21. The display device of claim 17, furthercomprising: a display driving circuit disposed on a second surface ofthe display panel in the sub-region; and a display circuit boardattached to the lower panel sheet in the main region and a portion ofthe display panel in the sub-region.
 22. The display device of claim 17,further comprising: a protective layer disposed on a second surface ofthe filling member, wherein the lower panel sheet may include: anembossed layer spaced apart from the display panel with the protectivelayer therebetween; a cushion layer spaced apart from the protectivelayer with the embossed layer therebetween; and a heat dissipation layerspaced apart from the embossed layer with the cushion layertherebetween.
 23. The display device of claim 17, wherein thefingerprint sensor includes an ultrasonic fingerprint sensor, andwherein the ultrasonic fingerprint sensor is configured to compare anincident ultrasonic wave which is transmitted upward from the ultrasonicfingerprint sensor with a fingerprint reflection ultrasonic wave whichis reflected from a finger on the fingerprint sensor, and recognize afingerprint of the finger.